Automatic belt adjuster



Aug. 11, 1931. I H. J BRUNK 1,813,685

' AUTOMATIC BEIL'I' ADJUSTER Filed Feb. 24, 1927 3 Sheets-Sheet 1 Aug. 11, 1931. H. J. 'BRUNK AUTOMATIC BELT ADJUSTER Filed Feb. 24, 1927 3 Sheets-Sheet 2 Ewen/tor Aug. 11, 1931. H. J. BRUNK' xuwouA'rIc BELT ADJUSTER Filed F eb. z4,' 1927 3 Sheets-Sheet 3 i HAROLD J.

Patented Aug. 1 1, 1931 THE 0. F. PEASE COMPANY, A oonronn'rron OF DELAWARE 1 AUTOMATIC BELT ADJUSTER Applicationqfil ed February 24,1927. Serial No.170,560.

My invention relates to improvements in automatic belt adjusters. I j

i In using endless belts of fabric or other material on machines for making blueprints,

I '5 machines for drying the'same, or on paper making machines where a wire screenis used, and n fact on all machines of like character, dlfliculty is always encountered 1I1 preventing the travel ofthe belt from side to side on the supporting rollers. Various manually operated adjustments have been provided heretofore, but as they require manipulation and depend on the judgment of the operator,

the results are seldom satisfactory. Where one of the rollers is adjustable, the operator usually draws one end of'said roller toward himself to cause the belt to travel toward its normal position and if it subsequently moves toorfar. he draws the otherend toward him,

andso on, continually moving the adjustable roller farther away from the other roller or i rollers. Thus the belt is stretched and even tually. breaks. Furthermore, the operator frequently adjusts the roller in the wrong direction since the operation is just the reverse from what it would be with a leather belt traveling on a-c'rowned pulley. g

The objectof the present invention is to overcome these," difficulties by providing means for automaticallymoving the belt back and forth toward its normal position when it travels towardone side or the other. 3 In the accompanying drawings, the invention is illustrated as being embodied in a blueprint drying machine, although it is adapted for use in numerous other classes of service. i

Figure 1 is a sectionalelevation of part of a machine for drying photographic prints.

Fig. 2 is a top planview of thefront portion thereof. I

Fig. 3 is an enlarged plan view, partly in section, of the same portion. 7

. Fig; 4 1s a sectionalelevation of said portion of the machine.

Fig. 5 is a section on line 5-5, Fig. 4;. i 7

Fig.6 is a section on line 66, Fig. 4.

Fig.:7-is a section on. line 77,' Fig. 4.;

{ Fig. 8 is an enlarged sectional elevation-of certain mechanism for limiting the number of turns of the "automatic adjusting device.

. Fig. 9 is asection on line 99, Fig. 8.

. Fig. 10 is a section on line 1010, Fig.8, and

Fig. llis an enlarged sectional elevation of amodification of. oneend of the adjust able roller.-

Blueprint drying machines. may include suitable side-fra1ne members 10 carrying be:

BRUNK, OF'CH'ICAGO, ILLINOIS, ASSIGNOR, BY MESNE ASSIGNMENTS," To

tween them rollers 11,12, 13 and 121, and a;

drying drum 15. An endless belt l 6- passes over the guide rollers'll, .12, 13' and l4, and part way aroundthe-drying drum 15.. Said drum'is heated by any'suitable means (not shown) and the blueprints or other prints to be dried are laid onthe belt 16and travel in thesame directionof the.arrow.in F ig. 1, be-

ing "carried around the heatingdrum. and

dried. f y,

The belt 1 6 Inay be several feetlwide and may be made of fabric, such as canvas, for

example. Eventhough said belt is properly adjusted initially,-itmay elongate, due to the continual feeding-of wet paper on one side or the other, as wellasin the middle, permitting said belt to stretch more and more. This stretching at the side tends to causetheabelt to travel from the middle to one side or the other. In. a machine of this character, the .difiiculties, due to side travelof the belt, are

probably greater. than in machines of any other types,.and such a machine therefore will illustrate well the advantages of the present. invention. 7 I. Generally speaking, the construction ofthe automatic belt adj usteris such that the roller or cylinder 11 rotates freely about its support,-

ing shaftj'17, but-has at each end means actuated by'the belt, for causing positiveengagee ment between said roller and 3 said shaft, whereby the twowillturn concurrently. At

I one end theengagement is direct, so that the roller turns in the same direction as the shaft,

whereasatfthe other end there are interposed planetary gears whereby-the shaft is made to rotate-in the opposite direction from said roller. [The shaft is pivotally supported at one end one; vertical axis, the other end being free to. move back and forth ashort distance position,

in a horizontal plane in the arc of a circle. The rotation of said shaft about its own axis, in one direction or the other, causes said other end to swing back and forth, thereby causing the belt to travel from one side toward the other, in a direction to restore it to normal its movement away from normal position causing the rotation of said direction or the other.

This mechanism will now be described more in detail. Referring to Figs. 3 and 4, a casting 18 is adjustably mounted on a screw threaded rod 19 secured to the frame 10 of the machine and has a vertical pivot pin 20 forming a pivotal support for the right-hand end of the shaft 17 by virtue of an aperturcd web 21 on a member 22 which carries a ball bearing raceway 23 mounted on the end of said shaft. A pinion 24 (see Fig. 5) is secured to said shaft and meshes with one or more pinions 25 mounted on a shaft or shafts 26 supported in the member 22. The pinion 25 meshes with an annular gear 27 secured to a ring 28 carrying a circular member 29 (see Fi .6) with ratchet teeth 30 on its periphery. n order to lock the cylindrical roller 11to the shaft 17, I may provide a number of pivoted pawls 31 near the end thereof, arranged to project outwardly through slotsin said roller, said pawls being pivoted at 32 to a casting 33 arranged to rotate freely on the shaft 17 and supporting the end of said roller. A preferred form of pawl is shown in Fig. 11, hereinafter referred to. Springs 34 are mounted in recesses in the casting 33 and normally press the pawls outwardly, whereby they normally clear the ratchet teeth 30. The roller 11 and casting 33' turn together, the latter turning freely about the, shaft 17 on a ball-bearing raceway35, the other end of said roller also turning on ball-bearings as hereinafter described.

The belt 16, under normal conditions, occupies the dotted line position, shown in Fig.

'2; that is to say, it is arranged centrally on the roller 11. However, if it should travel to the right, it would depress the pawls 31 against their springs, causing said pawls to engage the ratchet teeth and thereby rotate the planetary gears 24, 25 and 27 thereby rotating shaft 17 in the opposite direction, this rotation resulting in moving theleft hand end ofsaid shaftaway from the operator, in other words inwardly, whereupon the belt travels slowly back toward mid -position until further correction is required.

At the left hand end of said roller 11 (Fig. 4) a somewhat similar arrangement is provided, including pawls 36 pivotally supported at 37, in a casting 38, which supports the end of said roller (Fig. 7,) said casting bein freely rotatable about the shaft 17 on a ball aring raceway 39. The pawls 36 are normally held in outward position by springs 40, mounted in recesses in the casting 38. The

shaft, in one end of the cylinder is closed by a circular plate 41, fast on the shaft 17 and having ratchet teeth 42 on its periphery to be engaged by the pawls 36 when the belt works over to the left hand end of said roller (as viewed from the front of the machine) thereby causing the roller and the shaft to turn together and actuate mechanism for moving that end of the shaft outwardly; that is, toward the operator. p I i The mechanism for moving the end of the shaft back and forth in the arc of a circle, causing the belt to move from one side of the roller toward the middle thereof, will now be described. The left-hand end of the shaft 17, shown in Fig. 4:, is supported in aballbearing raceway 43 mounted in a traveling head 44, which provided with upper and lower rollers 45, permitting it to move back and forth on flat surfaces provided in the yoke 46, and has a third roller 47 engaging the head of a bolt 47 to limit end movement of the shaft 17. Said shaft has a worm gear l8 near the end thereof meshing with a gear 49 mounted on a shaft 50. The rear end of said shaft, as shown in Fig. 8, has a universal joint 51 with an extension shaft 52, whereby a head 53 and a cylinder'54l, in which said head is received, may be rotated in one direction or the other, depending on the rotation of the shaft 17, said head and cylinder having a splined connection (See Fig.9). Said cylinder carr'es'a plurality of springs 55 which press radially inward on corresponding plungers 56 maintaining the latter in engagement normally with ratchet teeth 57 on the periphery of a cylindrical member 58 re ceived within said cylinder 5%. See Figs. 8, 9 and 10. Saidcylindrical member 58 has a screw threaded shaft 59 at one end which may rotate in a fixed nut 60 secured to the frame of the machine whereby rotation of said cylindrical member in one direction or the other will cause it to move toward the front or rear of the machine. Said member has a groove 61, which when the belt is traveling properly, is positioned about midway between the two plungers 56. The cylindrical member 58 has a shaft 62 projecting from its end supported in a sliding head 63. A screw 6 f or other suitable means holds the head 63 to the head 53, although in this particular machine the axle of roller 14; is, in practice, received in bearings which are spring impolled in a direction to maintain tension on the belt and thus the sliding head 44 would be drawn rearwardly, in any case, without this fastening. The rear end of the cylinder '54 is providedwith a groove 65 which receives a lug 66 secured to the frame 10 (Fig. 3) thereby preventing longitudinal movement of said cylinder during its rotation.

It will be seen the arrangement is such that upon rotation of the cylinder 54: one of toward its central position In other Words, the mechanism provides for a predetermined number of rotation'sof the cylindrical member 54. When the cylinder rotates in the oppositedirection, the other plunger 56 becomes effective to rotate the cylindrical member 58 in the opposite direction, thereby causing it to slide in a direction the reverse of the sliding movement just described. With this construction, as the belt gradually'works to the left-hand end ofthe roller 11, as seen in Fig. 2 for example, the supporting shaft 17 begins to rotate in the same direction that roller 11 is rotating, and at the same time its left-hand endis swung outwardly a little, aboutthe right-hand end as a pivot, causing the belt to travel back i preferred form of pawl and mechanism is shown in Fig. 11, at the ends of the roller 11, the pawls 67 being pivoted at the opposite ends, as compared with'those previously described, and having pins 68 projecting therefrom, which pins normally clear a series of openings 69 in a plate 7 0, secured to the shaft 17. Said openings are spaced equidistant from each other and at; the same radii from the center of said shaft, whereby the pins 68, when projected outwardly by the rotation of the pawls 67 about'their pivotalsupports, will'enter the nearest opening and thus lock the roller 11 to the shaft 17, or at the other end of said, roller will cause the operation of the planetary gears. V Said pawls are of such configuration that the belt does not ride up on them graduallyas'with the first pawls described, but engages the top surfaceof the pawl as the roller is turning and assaidpawl is passing from one span of the belt to the other, providedfsaidbelt has worked far enough to one side to overlie the top corner of said pawl, as it appears in dotted lines in said figure. Withthis arrangement, a comparatively small move ment of the belt toone side or'the other from normal position will result in renderingthe pawls fully effective.

, As the return movement ofthe belt takes place very slowly (possibly vanhour to an hour and a half under some conditions) the adjustable end offthe shaft will not require. any more movement that what is sufficient to start the return movement of the belt. "For this reason, the correction is limited to that corresponding to a definite determined numratchet berof rotations of the correcting mechanism,

otherwise the. belt would be stretched atoneside' and possibly torn or broken. It is .al-

most impossibleto obtain wide belts or hands of. thischaracter which are of exactlythe p,

same length on both edges, and for :that .rea I son-the travel of the belt one way or the other begins almost immediately. When anew belt is applied, and after the roller has been properlyiadjust'ed, it may continue to travel in midpositionifor several hours, except as it may be efi'ected by unusualconditions. For example, placing blueprints more on one side of the belt than on the other not only-will cause an increased thickness when the prints are travelingaround the heating drum, but

the moisture from the wet prints .will cause a change. in the length of one side of the belt as compared with the other. 7

With the improvements described herein, however, all these irregularities are automatically compensated for, and the belt contheoretically perfect location. Under some conditions, theedge of the'belt is irregular so that the pivoted pawls work intermittently as parts of said edge overlap them. In

either case, however, the mechanism operates to relieve the operator of the necessity of the manual adjustment. Furthermore, the life of the belts is greatly prolonged as, with the automatic adjustment, the roller remains in the same average position at all times, whereaswith the previously used manualadj ustment, the tendency was to move the roller fined to a position not far removed fromits farther and farther away from'theother;

rollers over which the belt traveled, thereby continually stretching it; With my improvement as thebelt stretches gradually, due to continued use, the roller 14 takes up the slack, and the right hand end -'of the roller 11 and'shaft 17 may be movedoutwardly to whatever extentis necessary, by manu'aladjustment of the screw threaded rod 19- passing through the casting 18, without effecting the automatically operated meansfor maintaining the'belt in midposition. r

'- 'What Iclaim as new is: i

' 1. The combination with a frame,- of a roller, a pivotal support for one end of said roller, adjustable longitudinally of said 3 frame, 'a' carrier for the other end of said roller, wheels thereon, a track associated with said frame, on which said-rollersand carrier are permitted" a limited movement longitudinally of'said frame in'either of twodi- I rections from "mid-'position-,'a belt traveling over and rotatingsaid roller, means actuated by said belt upon deviation thereof from its normal position between the ends of said roller for moving said carrier alongsaid track to'shift the axis of rotation'of said "roller and cau'se'said belt to travelin a direction opposlte to sald deviation movement,and means for, stopping the travel of said carrier-beiso and a roller normally rotatable thereon, of

a belt passing over said roller, and a pawl and ratchet mechanism near one end of said roller normally inoperativebut rendered operative by said belt overlying said pawl, means carried by said roller for causing said shaft to rotate in the opposite direction from said roller and means cooperating with said shaft when rotatingto vary its axis of rotation.

3. In combination, a pair of sideframes, a shaftextendingbetween thetwo, a pivotal connection between one end of said shaft and one side frame, means arranged to slide back and forth on said other side frame and carrying the other end of said shaft, a roller normally rotatable about said shaft, a pawl and ratchet mechanism associated with each end of said roller and shaft to mechanically connect the roller and shaft, one pawl and ratchet being arranged to lock saidroller to said shaft causing the same to turn together, gearing associated with the other pawl and ratchet mechanismto cause said shaft to rotate in the opposite direction from said roller when said pawl and ratchet engage each other and means whereby the rotation of said shaft causes said first means to slide one way or the other, not to exceed a predetermined distance. p

s 4. In combination, a pair of side frames, a shaftextending between the two, a pivotal connection between one end of said shaft and one side frame, means arranged to slide back and'forth on said other side frame and carrying theother end of said shaft, a roller normally rotatable about said shaft, a pawl and ratchet mechanism associated with each end of said roller and shaft tomechanically connect the roller and shaft, one pawl and ratchet being arrangedto lock said roller to said shaft causing the same to turn together, and gearing associated with the-otherratchet mechanism to cause said shaft to rotate in the opposite direction from said roller when said pawl and ratchet engage each other, a belt passing over said roller, said pawls being arranged beyond the edges of said belt but adapted to be engaged by one edge or the other when said belt deviates from its normal position on said roller.

,7 5. In: combination, a pair of side frames, a shaft extending between the two, a pivotal connection between one end of said shaft and oneside frame, means arranged to slide back and forth on said otherside frame and cartying and ratchet mechanism associated with each end of said roller and shaft to mechanically connect the roller and shaft, one pawl and ratchet being arranged to lock said roller to said shaft causingthe same to turn together,

the other end of said shaft, asroller' normally rotatable about said shaft, a pawl gearingassociated with the other pawl and ratchet mechanism to cause said shaft to rotate'in the opposite direction from said roller when said pawland ratchet engage each other, a belt passing over said roller, said pawls being arranged beyond the edges of said belt but adapted .to be engaged by one edge or the other when said belt deviates from its normal position on said roller, and means for moving the slidable end of said shaft back and forth a predetermined amount depending on the direction of rotation of said shaft.

6. In a device of the class described, a rotatable shaft, a roller surrounding the same and normally turning freely thereon, said roller having a slot at each end, a pawl pivoted near each slotted end and projecting through the same above the surface of the roller, ratchet mechanism associated with said pawls normally out of engagement therewith, a planetary gear system associated with one ratchet'and with said shaft to cause the shaft to rotate in a direction opposite to that of said roller when said pawl and ratchet are in engagement, the other ratchet serving to cause said shaft to turn with said roller when the corresponding pawl engages said ratchet, and a belt passing over said roller between said pawls and normally clearing the same but adapted upon travel toward either end of said roller to overlie one pawl or the other to cause the engagement thereof with the corresponding ratchet,

7 In a device of the class described, a rotatable shaft, a roller surrounding the same and normally turning freely thereon, said roller having a slot at each end, a pawl pivoted near each slotted end and projecting through the same above the surface of the roller, ratchet mechanism associated with said pawls normally out of engagement therewith, a plane tary gear systemvassociated with one ratchet and with said shaft to cause the shaft to rotate in a direction opposite to that of said roller when said pawl and ratchet are inengagement, the other ratchet serving to cause said shaft to turn with said roller when the corresponding pawl engages said ratchet, a belt passing over said roller between said pawls and normally clearing the same but adapted upon travel toward either end of said roller to overlie one pawl or the other to cause the engagement thereof with the corresponding ratchet, a sliding support forming a bearing for one end of said shaft, and means actuated by the rotation of said shaft for moving said bearing back or forth in a direction to cause said belt to return toward its normal position on said roller.

v8. An attachment for photoprint dryers having a roller and a belt passing over the same comprising, a rotatable shaft, a worm and gear connection at one end thereof, a sliding support for said worm and gear, a

shaftrotated by said gear having oppositely disposed ratchet surfaces, a pair of pawls engaging, said surfaces and rotatable with said gear, whereby one pawl may rotate the ratchets in one direction and the other pawl in the other, and means for causing a longi-' tudinal movement of said ratchet surfaces during rotation thereof, wherebysaid pawls e are caused to slide along said ratchets during such rotation toward the end thereof whereupon one or the other of said'pawls becomes disengagedfrom the corresponding ratchet thereby terminating the rotation thereof.

9. An attachment for photoprint dryers having. a roller and a belt passing over the same, of a shaft supporting said roller having a pivotal support at one end and a sliding head constitutinga bearing at the other end, a stationary nut, a screw-threaded shaft passing through the same associated with said shaft at said head, a clutch whereby said roller shaft may rotate said screw threaded shaft inone direction orthe other to cause a longitudinal movement thereof and thus slide said head back and forth, and means for rendering said clutch ineffective after a predetermined number of rotations.

10. In a device of the class described, a rotatably mounted shaft, ball bearing raceciated with each end of saidroller and having perforations therein to be engaged by one end of a pawl, and gearing associated with one of said discs and said supporting my name. i

' v HAROLDJ. BRUNK.

ways on said shaft on opposite ends thereof, two members surrounding said shaft and turning on said ball bearings, each member having a plurality of pawls pivoted thereto, a spring associated with each member and each pawl normally pressing the same outwardly, a roller also supported on said members and having slots near its ends through which the pawls project, and a belt'partially surrounding saidroller and 'rotatii'ig the same but normally clearing said pawls, a ratchet member associated with each end of said shaft and arranged to be engaged by the corresponding pawls'when the latter are depressed by said belt traveling to one side of its central position to cause such engagement v of said pawls with the corresponding ratchet, and planetary gearing associated with one of said ratchets for rotating said shaft in a direction the reverse of that of said roller.

11. An attachment for photoprint machinery having a roller and a belt passing over the same, comprising a shaft support- I ing said roller having a pivotal support at one end and a sllding head constltuting. a

bearing at the other end, a stationary nut, a

V movement thereofand thus slide said'head back and forth, means for rendering said clutch ineffective after a predetermined number of rotations, saidroller having pawls associated with the end thereof, a disc asso- 

